The present invention relates to pulse generation and, in particular, to a sub-nanosecond multi-megavolt pulse generator. Pulse power development in the United States has been basically motivated by the desire to create simulation of nuclear weapons effects. A paper entitled "Pulsed Power For EMP Simulators" by Ian D. Smith and Harlan Aslin, IEEE Transactions on Antennas and Propagation, Vol. AP-26, No. 1, January 1978, provides a good overview of the development of pulse power simulators. Difficulty with the prior art pulse generators is often encountered in an attempt to develop magavolt or greater pulses with rise times of less than a nanosecond. Existing methods for generating multi-megavolt pulses with rise-times less than 10 ns use spark gaps. Typically, a multimegavolt Marx generator is used to develop a current which is built up comparatively slowly in a "peaking" capacitor in a time long compared with the desired voltage rise time. FIG. 1 shows a typical prior art scheme. The current in the "peaking" capacitor C2 is suddenly diverted to flow into load Z. This sudden diversion can be achieved in 1-10 ns. The limitations on the suddenness with which this build-up of current in load Z can be performed includes stray inductance and capacitance in the spark gap and spark channel and the rate at which the spark channel becomes conductive. The pulse generator of the present invention overcomes these difficulties experienced with prior art generators.